Continuously higher demands on the performance capability of the surgical microscope has accompanied advances in medical and surgical techniques. The surgical microscopes provide a stereomicroscopic view of the operating area. The surgical microscope should be easy to operate and set to the operating area without difficulty so that its use does not demand skill or intellectual concentration by the surgeon thereby allowing the surgeon to devote his undivided attention to the surgery.
For difficult surgical techniques, it is often essential for the success of the surgery that the surgeon can view a limited location in the region of the surgery from all spatial directions. This operating region is referred to as the surgery point in the description which follows.
Swiss Patent 482,439 discloses an adjustable viewing arrangement having an optical viewing device and a headrest for the surgeon. The headrest makes it possible for the surgeon to adjust to various viewing directions with a movement of the head and to maintain the focus adjustment of the surgical microscope. The success of this arrangement in practice is held within limits because the head movement of the surgeon required for adjusting the surgical microscope to another viewing direction detracts the surgeon with respect to concentration on the actual surgery.
U.S. Pat. Nos. 4,339,100 and 4,344,595 describe a stand for a surgical microscope and are incorporated herein by reference. This stand permits the surgeon to spatially guide a surgical microscope about a surgery point utilizing motors or manually and to maintain the focus adjustment. The movement of the surgical microscope about a surgery point with this stand requires skill and experience from the surgeon if the focusing adjustment of the surgical microscope is to be maintained during the movement.